A packed bed bioreactor (PBBR) was developed
for rapid establishment of nitrification in brackish
water hatchery systems in the tropics. The reactors were
activated by immobilizing ammonia-oxidizing (AMONPCU-
1) and nitrite-oxidizing (NIONPCU-1) bacterial
consortia on polystyrene and low-density polyethylene
beads, respectively. Fluorescence in situ hybridization
demonstrated the presence of autotrophic nitrifiers belong
to Nitrosococcus mobilis, lineage of b ammonia oxidizers
and nitrite oxidizer Nitrobacter sp. in the consortia. The
activated reactors upon integration to the hatchery system
resulted in significant ammonia removal (P\0.01) culminating
to its undetectable levels. Consequently, a
significantly higher percent survival of larvae was observed
in the larval production systems. With spent water the
reactors could establish nitrification with high percentage
removal of ammonia (78%), nitrite (79%) and BOD (56%)
within 7 days of initiation of the process. PBBR is configured
in such a way to minimize the energy requirements
for continuous operation by limiting the energy inputs to a
single stage pumping of water and aeration to the aeration
cells. The PBBR shall enable hatchery systems to operate
under closed recirculating mode and pave the way for
better water management in the aquaculture industry.

E¡ect of an extraction method on the structure of
glucan and its immunostimulatory response in Fenneropenaeus
indicus was investigated. Here we extracted
alkali insoluble glucan (AIG) and alkali
soluble glucan (ASG) from a ¢lamentous fungi Acremonium
diospyri following alkali^acid hydrolysis and
the sodium hypochlorite oxidation and dimethyl
sulphoxide extraction method respectively. Structural
analysis showed that 85% of glucan in AIG was a
(1 !3)-b-D-glucan and it increased the prophenoloxidase
and reactive oxygen intermediate activity
when administered to F. indicus. On the other hand,
ASG, which contained 93% (1 !3)-a-glucan, did
not induce signi¢cant immune response in shrimp.
Here we report that the di¡erence in immunostimulatory
potential between AIG and ASG is due to the
di¡erence in the percentage of (1 !3)-b-D-glucans
present in each preparation, which varies with the
method of extraction employed. Also our observations
suggest that glucan can be used as a potential
immunostimulant to shrimp, provided it contains
(1 !3)-b-D-glucan as the major fraction.

White Spot Syndrome Virus (WSSV) is the most devastating disease affecting shrimp culture around the
world. Though, considerable progress has been made in the detection and molecular characterization of WSSV
in recent years, information pertaining to immune gene expression in shrimps with respect to WSSV infection
remains limited. In this context, the present study was undertaken to understand the differential expression
of antimicrobial peptide (AMP) genes in the haemocytes of Penaeus monodon in response to WSSV infection
on a time-course basis employing semi-quantitative RT-PCR. The present work analyzes the expression profile
of six AMP genes (ALF, crustin-1, crustin-2, crustin-3, penaeidin-3 and penaeidin-5), eight WSSV genes (DNA
polymerase, endonuclease, immediate early gene, latency related gene, protein kinase, ribonucleotide
reductase, thymidine kinase and VP28) and three control genes (18S rRNA, β-actin and ELF) in P. monodon in
response to WSSV challenge. Penaeidins were found to be up-regulated during early hours of infection and
crustin-3 during late period of infection. However, ALF was found to be up-regulated early to late period of
WSSV infection. The present study suggests that AMPs viz. ALF and crustin-3 play an important role in
antiviral defense in shrimps. WSSV gene transcripts were detected post-challenge day 1 itself and increased
considerably day 5 onwards. Evaluation of the control genes confirmed ELF as the most reliable control gene
followed by 18S rRNA and β-actin for gene expression studies in shrimps. This study indicated the role of
AMPs in the protection of shrimps against viral infection and their possible control through the up-regulation
of AMPs

Chitosan is a biocompatible and biodegradable natural polymer with established
antimicrobial properties against specific microorganisms. The present study demonstrates its
antibacterial activity against 48 isolates of Vibrio species from prawn larval rearing systems. The
antibacterial activity had a positive correlation with the concentration of chitosan. This work opens
up avenues for using chitosan as a prophylactic biopolymer for protecting prawn larvae from
vibriosis.

White spot syndrome virus (WSSV), the most
contagious pathogen of cultured shrimp, causes mass
mortality, leading to huge economic loss to the shrimp
industry. The lack of effective therapeutic or prophylactic
measures has aggravated the situation, necessitating the
development of antiviral agents. With this objective, the
antiviral activity in the aqueous extract of a mangrove plant
Ceriops tagal in Penaeus monodon was evaluated. The
Ceriops tagal aqueous extract (CTAE) was non-toxic to
shrimps at 50 mg/ml when injected intramuscularly at a
dosage of 10 lL/animal (0.5 mg/animal) and showed a
protective effect against WSSV at 30 mg/ml when mixed
with WSSV suspension at a 1:1 ratio. When the extract was
administered along with the diet and the animals were
challenged orally, there was a dose-dependent increase in
survival, culminating in 100 % survival at a concentration
of 500 mg/kg body weight/day. Neither hypertrophied
nuclei nor the viral envelope protein VP28 could be demonstrated
in surviving shrimps using histology and indirect
immunofluorescence histochemistry (IIFH), respectively.
To elucidate the mode of action, the temporal expression of
WSSV genes and shrimp immune genes, including antimicrobial
peptides, was attempted. None of the viral genes
were found to be expressed in shrimps that were fed with
the extract and challenged or in those that were administered
CTAE-exposed WSSV. The overall results suggest
that the aqueous extract from C. tagal can protect
P. monodon from white spot syndrome virus infection.

The fresh water prawn, Macrobrachium rosenbergii, has proven potential for use as an
aquaculture species (Hanson & Goodwin, 1997; Kurup, 1984). In India alone, culture of
this species of prawn in low saline areas requires about 200 million seed per year
(Kurup, 1984). In hatcheries poor survival rate has been associated with vibriosis at
di#erent stages of the larval cycle. Members of the family Vibrionaceae associated with
the larvae of M. rosenbergii were shown to be pathogenic under laboratory conditions
(Bhat et al., 2000, in press). Vibrios have been associated with mortality of penaeid
prawns by several workers (Aquacop, 1977; Hameed, 1993; Karunasagar et al., 1994).
Two methods have been suggested to protect both the larvae and juveniles from
vibriosis; one is the administration of bacterins prepared from pathogenic strains
(Itami et al., 1989, 1991; Adams, 1991; Song & Sung, 1990; Sung et al., 1991) and the
other is the utilization of yeast 1-3 and 1-6 glucans as immunostimulants for
enhancing the non-specific defense system (Sung et al., 1994; Song et al., 1997). In the
light of these observations it was hypothesised that bacterins and yeast glucans may
also be e#ective in protecting the larvae of M. rosenbergii from vibriosis as has been
achieved in the case of penaeids. To examine this hypothesis, the ability of bacterins
and an extracellular glucan-producing yeast to increase the overall survival and
metamorphosis of larvae in a hatchery, as well as to protect against an experimental
challenge under laboratory conditions, was evaluated

Lack of shrimp cell lines has hindered the study of pollutants which adversely affects shrimp health and
its export value. In this context a primary haemocyte culture developed from Penaeus monodon was
employed for assessing the cytotoxicity and genotoxicity of two heavy metal compounds, cadmium
chloride and mercuric chloride and two organophosphate insecticides, malathion and monocrotophos.
Using MTT assay 12 h IC50 values calculated were 31.09 16.27 mM and 5.52 1.16 mM for cadmium
chloride and mercuric chloride and 59.94 52.30 mg l 1 and 186.76 77.00 mg l 1 for malathion and
monocrotophos respectively. Employing Comet assay, DNA damage inflicted by these pollutants on
haemocytes were evaluated and the pollutants induced DNA damage in >60% of the cells. The study
suggested that haemocyte culture could be used as a tool for quantifying cytotoxicity and genotoxicity of
aquaculture drugs, management chemicals and pollutants

Occurrence of black yeasts in the slope sediments of Bay of Bengal was investigated during FORV Sagar Sampada cruises 236 and 245. The black yeast population was found to be very scanty in the area and the isolates could be obtained from 200m to 1000m depth regions in the slope sediments. The isolates were identified as Hortaea werneckii by Internal Transcribed Spacer (ITS) sequencing. The biodegradation potential of these strains was found to be very high with all the strains exhibiting protease, lipase and amylase production. The optimum growth conditions were pH 8, salinity 30 ppt and temperature 30oC. The pigment melanin, in these organisms was identified to be of dihydroxynaphthalene type by NMR. The melanin was found to exhibit inhibitory activity against different human and fish pathogens. Melanin degrading enzyme could also be extracted from these organisms

A Pseudomonas sp PS-102 recovered from Muttukkadu brackish water lagoon, situated south of Chennai, showed significant
activity against a number of shrimp pathogenic vibrios. Out of the 112 isolates of bacterial pathogens comprising Vibrio harveyi, V.
vulnificus, V. parahaemolyticus, V. alginolyticus, V. fluvialis, and Aeromonas spp, 73% were inhibited in vitro by the cell-free culture
supernatant of Pseudomonas sp PS-102 isolate. The organism produced yellowish fluorescent pigment on King's B medium,
hydrolysed starch and protein, and produced 36.4% siderophore units by CAS assay and 32 μM of catechol siderophores as
estimated by Arnow's assay. The PS-102 isolate showed wide ranging environmental tolerance with, temperatures from 25 to 40 °C,
pH from 6 to 8, salinity from 0 to 36 ppt, while the antagonistic activity peaked in cultures grown at 30 °C, pH 8.0 and at 5 ppt saline
conditions. The antagonistic activity of the culture supernatant was evident even at 30% v / v dilution against V. harveyi. The
preliminary studies on the nature of the antibacterial action indicated that the antagonistic principle as heat stable and resistant to
proteolytic, lipolytic and amylolytic enzymes. Pseudomonas sp PS 102 was found to be safe to shrimp when PL-9 stage were
challenged at 107 CFU ml−1 and by intramuscular injection into of ∼5 g sub-adults shrimp at 105 to 108 CFU. Further, its safety in a
mammalian system, tested by its pathogenicity to mice, was also determined and its LD50 to BALB/c mice was found to be 109 CFU.
The results of this study indicated that the organism Pseudomonas sp PS 102 could be employed as a potential probiont in shrimp
and prawn aquaculture systems for management and control of bacterial infections

In the present study, we investigated the
involvement of Aeromonas spp. in eliciting disease
outbreaks in freshwater ornamental fishes across the
state of Kerala, India. We investigated three incidences
of disease, in which the moribund fishes
exhibited clinical signs such as haemorrhagic septicemia
(in gouramy, Trichogaster sp.), dropsy (in Oscar,
Astronotus ocellatus) and tail rot/fin rot (in gold fish,
Carassius carassius). Pure cultures (n = 20 from each
fish; 60 in total) of Aeromonas spp. were recovered
from the abdominal fluid as well as from internal
organs of affected fishes, although they could not be
identified to species level because of the variations in
their phenotypic characters. The molecular fingerprinting
of the isolates using Enterobacterial Repetitive
Intergenic Consensus PCR proved the genetic
diversity of the isolates from the three sites. The
phylogenetic trees constructed using concatenated
sequences (using 16S rRNA, gyrA, gyrB and rpoD
genes) indicated that they were related to Aeromonas
veronii. They exhibited marked cytotoxic and haemolytic
activity, which were responsible for the pathogenic
potential of the isolates. The isolates possessed
multiple virulence genes such as enterotoxins (act and
alt), haemolytic toxins (aerA and hlyA), genes
involved in type III secretion system (ascV, aexT
and ascF–ascG), glycerophospholipid-cholesterol
acyltransferase (gcat) and a type IV pilus (tapA) gene,
as determined by PCR. Virulence of representative
isolates to goldfish was also tested, and we found LD50
values of 104.07–105.35 cfu/fish. Furthermore, the
organisms could be recovered as pure cultures from
the lesions as well as from the internal organs.

Chitosan has beenwidely accepted as awall material
for preparing microcapsules of various purposes in
human medicine. The possibility of using chitosan
as a wall material for microencapsulating nutrients
and drugs for aquaculture purposes, speci¢cally to
Macrobrachium rosenbergii larvae was evaluated in
this study. Two types of chitosan-coated microcapsules
were prepared using either acetone (MEC-A) or
NaOH (MEC-N) as the cross-linking agents. They
were compared with a microbound diet relative to
total leaching of nutrients and free amino acids
(FAA). Among the microcapsules, MEC-N showed
the lowest level of total leaching of nutrients (23.3%)
during 5 h of immersion in seawater and released
65% FAA after 60min. During laboratory trials,75%
larvae had accepted the MEC-N capsule. The results
of the study suggest that chitosan can be used as a
wall material for preparing microcapsules to deliver
drugs and nutrients to M. rosenbergii larvae.

This study investigated the enhancement of solar disinfection using custom-made batch
reactors with reflective (foil-backed) or absorptive (black-backed) rear surfaces, under a
range of weather conditions in India. Plate counts of Escherichia coli ATCC11775 were made
under aerobic conditions and under conditions where reactive oxygen species (ROS) were
neutralised, i.e. in growth medium supplemented with 0.05% w/v sodium pyruvate plus
incubation under anaerobic conditions. While the addition of either an absorptive or a
reflective backing enhanced reactor performance under strong sunlight, the reflective
reactor was the only system to show consistent enhancement under low sunlight, where
the process was slowest. Counts performed under ROS-neutralised conditions were slightly
higher than those in air, indicating that a fraction of the cells become sub-lethally injured
during exposure to sunlight to the extent that they were unable to grow aerobically.
However, the influence of this phenomenon on the dynamics of inactivation was relatively
small

A growth medium with Leibovitz-15 L-15.as the base, supplemented with foetal bovine
serum 10% vrv., fish muscle extract 10% vrv., prawn muscle extract 10% vrv., lectin
concanavalin A. 0.02 mg mly1., lipopolysaccharide 0.02 mg mly1., glucose D 0.2 mg mly1.,
ovary extract 0.5% vrv.and prawn haemolymph 0.5%. has been formulated with 354"10
mOsm for the development and maintenance of a cell culture system from the ovarian tissue of
African catfish, Clarias gariepinus. For its subculturing, a cell dissociationrextracting solution,
composed of equal portions of trypsin phosphate versene glucose TPVG. containing 0.0125%
wrv.trypsin and 25% vrv.non-enzymatic cell dissociation solution 1 and 2, has also been
developed with which the cell culture can be passaged 15 times after which they cease to multiply
and consequently perish. The cell cultures can be maintained for 12–15 days without fluid change
between the passages. This is the first report of a cell culture system from the ovarian tissues of
African catfish

Two ammonia oxidizing (AMOPCU-1 and AMONPCU-1) and two nitrite oxidizing (NIOPCU-1 and NIONPCU-1) consortia for activating nitrifying bioreactors and thereby establishing nitrification in penaeid and non-penaeid hatchery systems were developed by enrichment. For further amplification of the consortia a simple medium having seawater (either salinity 30 ‰ or 15 ‰) as base, supplemented with NH4+-N/NO2--N and PO4- and pH adjusted to 8 was identified. During the amplification in a fermentor the consortia exhibited excessive wall growth and diminished their yield coefficient posing difficulty in harvesting the cells completely. The consortia consisted of both Gram negative and Gram-positive bacterial cells embedded in a mucilaginous matrix of glycocalyx - like material presumably composed of polysaccharides. The consortia besides being useful in activating nitrifying bioreactors developed for shrimp/prawn hatchery systems can also be used as bioaugmentors in the bioremediation of ammonia and nitrite toxicity in aquaculture systems.

The immunostimulatory effect of an alkali insoluble glucan extracted from marine yeast isolate Candida sake
S165 was tested in Fenneropenaeus indicus. Post larvae (PL) of F. indicus, fed glucan incorporated diet at
varying concentrations (0.05, 0.1, 0.2, 0.3, 0.4 g glucan/100 g feed) for 21 days were challenged orally with
white spot syndrome virus (WSSV). Maximum survival was observed in PL fed the 0.2% glucan incorporated
diet. Subsequently the feed incorporated with 0.2% glucan was fed to F. indicus post larvae at different
feeding intervals, i.e. daily, once every two days, once every five days, once every seven days and once every
ten days. After 40 days, the prawns were challenged orally with WSSV and post challenge survival was
recorded. Shrimp feed containing 0.2% glucan when administered once every seven days gave maximum
survival. This was supported by haematological data obtained from adult F. indicus, i.e. total haemocyte count,
phenoloxidase activity and nitroblue tetrazolium reduction (NBT). The present observation confirms the
importance of dose and frequency of administration of immunostimulants in shrimp health management

The microalgal community as primary producers has to play a significant role in the biotic
and abitoic interactions of any aquatic ecosystem. Whenever a community is exposed to a pollutant,
responses can occur because individuals acclimate to pollutant caused changes and selection can
occur favouring resistant genotypes within a population and selection among species can result in
changes in community structure. The microalgal community of industrial effluent treatment systems
are continuously exposed to pollutants and there is little data available on the structure and seasonal
variation of microalgal community of industrial effluent holding ponds, especially of a complex
effluent like that of refinery. The aim of the present study was to investigate the annual variation in
the ecology, biomass, productivity and community structure of the algal community of a refinery
effluent holding pond. The results of the study showed the pond to be a eutrophic system with a
resistant microalgal community with distinct seasonal variation in species composition